Book/Report

FZJ-2018-03233

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Diffusion von Helium in kubischraumzentrierten und hexagonalen Metallen

Vaßen, R. P. (Corresponding author)FZJ*

1990
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/18728

Report No.: Juel-2354

Abstract: Foil specimens (2.5 - 85.0 $\mu$m) of V, Fe (bcc) and Ti, Co and Mg (hcp) were homogenously implanted with helium to final concentrations between 0.001 ppm and 5 ppm. By subsequent thermal desorption measurements three regimes of different desorption behaviour were identified: 1) Free diffusion determined the helium-release as long as the mean distance between a helium atom and the surface was small compared to the mean distance between the helium atoms. For Titanium a substitutional mechanismen was proposed, while in all the other metals helium diffuses by a dissociative mechanism with recapture at thermal vacancies (Mg, Co) andimplantation-induced vacancies (V, Fe), respectively. 2) Free diffusion was reduced by the agglomeration of helium atoms. The amount of helium released during free diffusion depended on the thickness d and the helium-concentration co as 1 / d $\sqrt{C_{0}}$. This dependence was explained by a simple agglomeration-model.3) After the formation of helium-bubbles a small heliumrelease persisted. This could be explained by two different coarsening mechanismens: bubble-migration and -coalescence (e. g. Mg) and Ostwald-ripening (e. g. Ti).

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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